STANDARD PROTOCOL FOR
MEASUREMENT OF FAN AND COOLING
SAVINGS FROM COMMERCIAL-SECTOR
PACKAGED ROOFTOP HVAC UNITS
Regional Technical Forum
March 13, 2012
Vast Contributions to Get to This Point
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Started 2004 - Five Phases of RTF work
Significant “Products” and “By-Products”
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Much simplified measurement approach (standard protocol)
Better understanding of RTU systems & opportunities
Better understanding of measurement and sampling error
RTU power measurement data library
New Honeywell controller
Dozens of dedicated individuals
Issue:
Highly Variable Savings by Site and by Program
From BPA 2009
Recent Steps to Get to Savings Methodology
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Complete collecting & storing the 12-month data
Set up a functioning data repository with open access
Determine confidence in annual savings methodology
Savings too variable for a UES – Need Protocol
Understand the persistence of fan schedules
Examine rooftop metered temperatures vs NOAA site
Initial Calculator developed
2009-2011 Research Funded by BPA via Cadmus.
Gets RTUG review & technical guidance.
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4
Reliability of savings method analyzed & tested
Data block analysis 10, 15, 21, 28 days
Refined seasonal windows for pre & post measurements
Calculator improved, streamlined, user-friendly & dependable
Standard Protocol conformed to guidelines
CT versus True Power tested and rejected (for now)
Scope of applicability refined
2011-2012 Development by
Coordinated RTF
RTU Subcommittee Involvement
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RTUG Meetings
– 2011: January, August, December
– 2012: January, February, March
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Protocol/Calculator Development Discussions
(Contractors, RTF staff, subcommittee members)
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December 7, 2011
December 19
January 31, 2012
February 9
February 16
RTU Subcommittee Members
Contractors: (NBI, NorthWrite, Cadmus, PECI, SBW) Mark Cherniack, Howdy
Reichmuth, Bill Koran, Josh Rushton, Reid Hart, Mike Baker
RTF Staff: Charles Grist, Mark Kendall
67 Members (Bold members participated in two or more protocol deliberations):
Alan Budman, Alan Mountjoy-Venning, Amy Patenaude, Anthony Hernandez, Bjorn
Jensen, Bob Davis, Bruan Van Buskirk, Buck Taylor, Chris Helmers, Dale Gustavson,
Dan Gaherty, Daniel Wilkinson, Danny Miller, Dave Baylon, Dave Robison, David
Davis, Fred Gordon, Glenn Hensen, Graham Parker, Greta Zink, Jack Callahan, Jack
Zeiger, Janice Peterson, Jeff Cole, Joe Schmutzler, John Palmer-Williams, Jon Linn,
Jon Powell, Jonathan Wooley, Justin Sipe, Karen Des , Srinivas Katipamula, KC Spivey,
Ken Keating, Kristin Heinmeier, Lauren Gage, Levi Westra, Marie McMahon, Mark
Jerome, Marshall Hunt, Mike Kennedy, Mike Little, Mike Lubliner, Mira Vowles, Nick
O'Neill, Paul Kyllo, Paul Needham, Peter Meyer, Jay Pilliod, Mark Rehley, Rob
Penney, Erin Rowe, Sean Gouw, Shea Dibble, Sherry Hu, Stan Price, Judith Stasack,
Danny Taasevigen, Tom Foley, Tom Leinhard, Will Miller, Will Price, Travis Reeder,
Alan Fraser
Standard Protocol Sections
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PURPOSE
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DEFINITION OF KEY TERMS
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ELIGIBLE SYSTEMS AND MEASURES
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– Rooftop package systems with constant speed supply fan +
constant or variable speed compressors
– Split systems
– Heat pumps in cooling/ventilation modes only –heating must
be turned off
REQUIRED COMMISSIONING
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SAMPLING PROCEDURE -NA
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SUNSET CRITERIA
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REQUIRED KNOWLEDGE AND SKILLS OF PRACTITIONER
Standard Protocol Sections-2
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DATA COLLECTION REQUIREMENTS
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PROVISIONAL DATA COLLECTION REQUIREMENTS- NA
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SAVINGS ESTIMATION STEPS
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ESTIMATE OF TYPICAL MEASUREMENT COST
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RELATIONSHIP TO OTHER PROTOCOLS/GUIDELINES
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USER’S GUIDE TO THE SAVINGS CALCULATOR
Final RTU Protocol Issues Raised & Addressed-1
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Test on multiple sites to better understand confidence interval
– Annual use estimates typically plus/minus 5%
– Savings estimates plus/minus 20% WHEN savings >25% of
annual use
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Confidence intervals are wide at the individual unit level
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Unit precision levels are low, but can have confidence in program
wide savings
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Limits of the protocol are stated with eligible measures identified and
in field measurement timing
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Calculator metrics for measurement error:
– R-squared and data range checks
RTU Protocol Confidence Limits
Limited Sites
Confidence Limit, % of
Annual Energy
Hi & Lo Confidence Limits as % of Annual Estimate
25%
20%
15%
10%
5%
0%
-5%
-10%
-15%
-20%
-25%
05/02/10
05/22/10
06/11/10
07/01/10
07/21/10
08/10/10
08/30/10
Beginning of 28 Day Metering Interval
lo-4
hi-4
lo-2
hi-2
• Confidence limits are normalized relative to annual energy
• Confidence limits highest for metering periods starting in late June to
mid-July
• Confidence limits of +- 5% are achieved with metering periods starting
in late May and early August
09/19/10
RTU Measure Savings Confidence
RTF Policy Considerations
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Guidelines call for 80% of cases to be +- 20%
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RTU confidence in pre- and post- are 5% of the annual use
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The effect of the 5% error on the savings is greater than 5%
example: 5% error applied to savings of 50% of annual = 10%
error relative to the savings
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When savings between pre and post are small Guidelines
standard may not be met
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Need consideration for small savings measures
Final RTU Protocol Issues Raised & Addressed-2
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Pre & Post measurement scheduling:
– Can we do Pre- in August and Post- in May?
o Yes, but additional effort required ~50% cost--need to fully
document set points/schedules and either leave monitoring on
all winter or take off/put on
– Can we do week-on/week-off testing?
o Yes, better way to test only for measures that can be turned
on/off. Few measures: controls-related/economizer; added labor
costs
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Eligible system/measures included, but not specifically tested
– split system
– variable speed compressor
– Demand Control Ventilation (depends on fan cycling/VSD)
Final RTU Protocol Issues Raised & Addressed-3
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System & Measure Exclusions—potential for ‘Provisional’
Protocol
– VSD supply fan, variable refrigerant flow
– Heat pump heating is in development, not yet ready for
Provisional Protocol, Savings Calculator cannot yet handle
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Hone & specify Protocol measurements: See Protocol Section 8
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Develop Savings Calculator steps: See Protocol Section 10
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Cost to implement the protocol revised: See Protocol Section 11
Annualized Energy Use / Savings
Calculator
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Working toward 3rd-party review of Protocol and
Calculator by PNNL
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Statistics package is of value—needs funding
– Regression stats development
– Annualization stats development
– Stats in Calculator output
– Charts of residuals/confidence intervals
– Chart for annualization uncertainty
Other Issues of Note
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Costs to implement the measurement protocol are not fixed, cost
estimates based on mature program and lessons learned
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Savings Calculator is for a single unit verification; not for program
evaluation
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When are savings too small to detect?
– Depends on measures applied to the RTU
– Alternate (lower cost) calculation options: changing fan schedule
during non-cooling hours--don’t need the Savings Calculator to
estimate savings, just multiply fan watts x time
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Protocols and calculators need ongoing, variable RTF support
– Need to add to 2013 work plan & budget
– Savings Calculator statistics package development
Program Evaluation Metering Sample Size
Sample sizes to achieve an 80% confidence > 20% precision
measurement for evaluating energy savings from similar programs
on similar sites
Sample sizes are not directly related to the per unit savings protocol and
Savings Calculator
RTUG Committee Recommendation
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RTUG is being polled for support and any
final comments on the proposed Standard
Protocol
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Will report results to RTF
Proposed RTF Motion
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The RTF approves the Rooftop Unit
Standard Protocol for active status
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Provisional Protocol to be developed for
future RTF consideration